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Merged
mroldx merged 1 commit into from
Apr 20, 2020
Merged

Update 二、集合框架.md #1

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9 changes: 6 additions & 3 deletions file/二、集合框架.md
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- 删除引起的不平衡：

最坏情况下，平衡二叉树需要维护从被删node到root这条路径上所有node的平衡性，因此需要旋转的量级是O(logN)此，而红黑树最多只需3次旋转，只需要O(1)的复杂度。

**5、JDK1.8中HashMap的插入源码分析**
**6、HashMap为什么要树化？**

- 本质上这是个安全问题。因为在元素放置过程中，如果一个对象哈希冲突，都被放置到同一个桶里，则会形成一个链表，我们知道链表查询是线性的，会严重影响存取的性能。而在现实世界，构造哈希冲突的数据并不是非常复杂的事情，恶意代码就可以利用这些数据大量与服务器端交互，导致服务器端CPU大量占用，这就构成了哈希碰撞拒绝服务攻击，国内一线互联网公司就发生过类似攻击事件。

**7、JDK1.8中HashMap的插入源码分析**

```java
/**
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## 6、总结

最主要的核心还是 **==Lambda== 表达式**和 **==Stream API==**
最主要的核心还是 **==Lambda== 表达式**和 **==Stream API==**